'Splain please re: mixer, alsa, pulseaudio and tvtime??

Michael Schwendt mschwendt at gmail.com
Sun Jul 26 06:08:42 UTC 2009

On Sat, 25 Jul 2009 22:18:54 -0400, William wrote:

> To get a clean start by first getting tvtime working with ALSA alone, I
> removed PulseAudio, rebooted and ran:

1) No need to reboot. You could have killed the pulseaudio daemon.

2) Since tvtime doesn't do any audio playback, it doesn't have much
(if anything) to do with PulseAudio. Since tvtime only accesses a mixer,
disabling PulseAudio ensures that you can control the ALSA mixer
channels without the sound server adding another layer (such as
offering its own master volume channel).

> ]$ amixer controls and amixer -c 0 controls

No need to keep specifying -c 0 anywhere as long as there is only
a single hardware device numbered by ALSA on your machine.
> Simple mixer control 'Line',0 -yes numid=14  -- the best/ but no sound

I wonder what kind of Line input this is? You keep on pointing out
that you haven't placed a cable between tv card and onboard audio,
but even with onboard audio 'Line' and 'Mic' are external input
jacks, aren't they?

> Simple mixer control 'Mic',0 -err

Interesting. Here, tvtime has no trouble using either of

  tvtime --mixer=default/Mic
  tvtime --mixer=hw:0/Mic
  tvtime --mixer=hw:0/'Mic'

Not that it makes any sense, since no mic is plugged in, but still tvtime
here succeeds in doing mute/unmute and changing the volume level.

> Simple mixer control 'PC Speaker',0 -yes numid=22

> Simple mixer control 'Capture',0 -err
> Simple mixer control 'Capture',1 -err

This is one of the special things about your audio chipset. Two
Capture lines, likely one analog and one digital.

> Simple mixer control 'Channel Mode',0 -err
> Simple mixer control 'Input Source',0 -err
> Simple mixer control 'Input Source',1 -err

Two input channel chosers, two. Your earlier alsa info output
showed that first one is Line and on, second one Mic and off.

> mixer: Can't open mixer hw0:Line, mixer volume and mute unavailable.
> mixer: Can't open device hw0, mixer volume and mute unavailable."

Syntax error. "hw0:" is invalid.

> $ tvtime --mixer=default/Speaker

Not available in your list of controls, but default/'PC Speaker' is.

> In every case, there was no sound.
Why do you still expect sound? Which component (hardware or software)
do you expect to "send sound" to your onboard audio chipset? And how?
ANd what does your tv card driver does related to audio?

We're going in circles, and that's why this is better continued in email
than in bugzilla.

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